Question

Office occupancy in a city is an indication of the economic health of the region in which it is located. A random sample of 165 offices in Boston was selected and it was found that 24 were vacant. A random sample of 145 offices in Chicago was selected and it was found that 17 were vacant.
a. Construct a 95% confidence interval to estimate the difference in vacancy rates between these two cities. What conclusions can be made?
b. Verify your results using PHStat.